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6de9cd9a DN |
1 | /* Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc. |
2 | Contributed by Andy Vaught | |
3 | ||
4 | This file is part of the GNU Fortran 95 runtime library (libgfortran). | |
5 | ||
6 | Libgfortran is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2, or (at your option) | |
9 | any later version. | |
10 | ||
11 | Libgfortran is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with Libgfortran; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | /* Unix stream I/O module */ | |
22 | ||
23 | #include "config.h" | |
24 | #include <stdlib.h> | |
25 | #include <limits.h> | |
26 | ||
27 | #include <unistd.h> | |
28 | #include <sys/stat.h> | |
29 | #include <fcntl.h> | |
30 | ||
31 | #include <sys/mman.h> | |
32 | #include <string.h> | |
33 | #include <errno.h> | |
34 | ||
35 | #include "libgfortran.h" | |
36 | #include "io.h" | |
37 | ||
38 | #ifndef PATH_MAX | |
39 | #define PATH_MAX 1024 | |
40 | #endif | |
41 | ||
42 | #ifndef MAP_FAILED | |
43 | #define MAP_FAILED ((void *) -1) | |
44 | #endif | |
45 | ||
46 | /* This implementation of stream I/O is based on the paper: | |
47 | * | |
48 | * "Exploiting the advantages of mapped files for stream I/O", | |
49 | * O. Krieger, M. Stumm and R. Umrau, "Proceedings of the 1992 Winter | |
50 | * USENIX conference", p. 27-42. | |
51 | * | |
52 | * It differs in a number of ways from the version described in the | |
53 | * paper. First of all, threads are not an issue during I/O and we | |
54 | * also don't have to worry about having multiple regions, since | |
55 | * fortran's I/O model only allows you to be one place at a time. | |
56 | * | |
57 | * On the other hand, we have to be able to writing at the end of a | |
58 | * stream, read from the start of a stream or read and write blocks of | |
59 | * bytes from an arbitrary position. After opening a file, a pointer | |
60 | * to a stream structure is returned, which is used to handle file | |
61 | * accesses until the file is closed. | |
62 | * | |
63 | * salloc_at_r(stream, len, where)-- Given a stream pointer, return a | |
64 | * pointer to a block of memory that mirror the file at position | |
65 | * 'where' that is 'len' bytes long. The len integer is updated to | |
66 | * reflect how many bytes were actually read. The only reason for a | |
67 | * short read is end of file. The file pointer is updated. The | |
68 | * pointer is valid until the next call to salloc_*. | |
69 | * | |
70 | * salloc_at_w(stream, len, where)-- Given the stream pointer, returns | |
71 | * a pointer to a block of memory that is updated to reflect the state | |
72 | * of the file. The length of the buffer is always equal to that | |
73 | * requested. The buffer must be completely set by the caller. When | |
74 | * data has been written, the sfree() function must be called to | |
75 | * indicate that the caller is done writing data to the buffer. This | |
76 | * may or may not cause a physical write. | |
77 | * | |
78 | * Short forms of these are salloc_r() and salloc_w() which drop the | |
79 | * 'where' parameter and use the current file pointer. */ | |
80 | ||
81 | ||
82 | #define BUFFER_SIZE 8192 | |
83 | ||
84 | typedef struct | |
85 | { | |
86 | stream st; | |
87 | ||
88 | int fd; | |
81f4be3c TS |
89 | gfc_offset buffer_offset; /* File offset of the start of the buffer */ |
90 | gfc_offset physical_offset; /* Current physical file offset */ | |
91 | gfc_offset logical_offset; /* Current logical file offset */ | |
92 | gfc_offset dirty_offset; /* Start of modified bytes in buffer */ | |
bf1df0a0 | 93 | gfc_offset file_length; /* Length of the file, -1 if not seekable. */ |
6de9cd9a DN |
94 | |
95 | char *buffer; | |
96 | int len; /* Physical length of the current buffer */ | |
97 | int active; /* Length of valid bytes in the buffer */ | |
98 | ||
99 | int prot; | |
100 | int ndirty; /* Dirty bytes starting at dirty_offset */ | |
101 | ||
102 | unsigned unbuffered:1, mmaped:1; | |
103 | ||
104 | char small_buffer[BUFFER_SIZE]; | |
105 | ||
106 | } | |
107 | unix_stream; | |
108 | ||
109 | /*move_pos_offset()-- Move the record pointer right or left | |
110 | *relative to current position */ | |
111 | ||
112 | int | |
113 | move_pos_offset (stream* st, int pos_off) | |
114 | { | |
115 | unix_stream * str = (unix_stream*)st; | |
116 | if (pos_off < 0) | |
117 | { | |
118 | str->active += pos_off; | |
119 | if (str->active < 0) | |
120 | str->active = 0; | |
121 | ||
122 | str->logical_offset += pos_off; | |
123 | ||
124 | if (str->dirty_offset+str->ndirty > str->logical_offset) | |
125 | { | |
126 | if (str->ndirty + pos_off > 0) | |
127 | str->ndirty += pos_off ; | |
128 | else | |
129 | { | |
130 | str->dirty_offset += pos_off + pos_off; | |
131 | str->ndirty = 0 ; | |
132 | } | |
133 | } | |
134 | ||
135 | return pos_off ; | |
136 | } | |
137 | return 0 ; | |
138 | } | |
139 | ||
140 | ||
141 | /* fix_fd()-- Given a file descriptor, make sure it is not one of the | |
142 | * standard descriptors, returning a non-standard descriptor. If the | |
143 | * user specifies that system errors should go to standard output, | |
144 | * then closes standard output, we don't want the system errors to a | |
145 | * file that has been given file descriptor 1 or 0. We want to send | |
146 | * the error to the invalid descriptor. */ | |
147 | ||
148 | static int | |
149 | fix_fd (int fd) | |
150 | { | |
151 | int input, output, error; | |
152 | ||
153 | input = output = error = 0; | |
154 | ||
155 | /* Unix allocates the lowest descriptors first, so a loop is not | |
156 | * required, but this order is. */ | |
157 | ||
158 | if (fd == STDIN_FILENO) | |
159 | { | |
160 | fd = dup (fd); | |
161 | input = 1; | |
162 | } | |
163 | if (fd == STDOUT_FILENO) | |
164 | { | |
165 | fd = dup (fd); | |
166 | output = 1; | |
167 | } | |
168 | if (fd == STDERR_FILENO) | |
169 | { | |
170 | fd = dup (fd); | |
171 | error = 1; | |
172 | } | |
173 | ||
174 | if (input) | |
175 | close (STDIN_FILENO); | |
176 | if (output) | |
177 | close (STDOUT_FILENO); | |
178 | if (error) | |
179 | close (STDERR_FILENO); | |
180 | ||
181 | return fd; | |
182 | } | |
183 | ||
184 | ||
185 | /* write()-- Write a buffer to a descriptor, allowing for short writes */ | |
186 | ||
187 | static int | |
188 | writen (int fd, char *buffer, int len) | |
189 | { | |
190 | int n, n0; | |
191 | ||
192 | n0 = len; | |
193 | ||
194 | while (len > 0) | |
195 | { | |
196 | n = write (fd, buffer, len); | |
197 | if (n < 0) | |
198 | return n; | |
199 | ||
200 | buffer += n; | |
201 | len -= n; | |
202 | } | |
203 | ||
204 | return n0; | |
205 | } | |
206 | ||
207 | ||
208 | #if 0 | |
209 | /* readn()-- Read bytes into a buffer, allowing for short reads. If | |
210 | * fewer than len bytes are returned, it is because we've hit the end | |
211 | * of file. */ | |
212 | ||
213 | static int | |
214 | readn (int fd, char *buffer, int len) | |
215 | { | |
216 | int nread, n; | |
217 | ||
218 | nread = 0; | |
219 | ||
220 | while (len > 0) | |
221 | { | |
222 | n = read (fd, buffer, len); | |
223 | if (n < 0) | |
224 | return n; | |
225 | ||
226 | if (n == 0) | |
227 | return nread; | |
228 | ||
229 | buffer += n; | |
230 | nread += n; | |
231 | len -= n; | |
232 | } | |
233 | ||
234 | return nread; | |
235 | } | |
236 | #endif | |
237 | ||
238 | ||
239 | /* get_oserror()-- Get the most recent operating system error. For | |
240 | * unix, this is errno. */ | |
241 | ||
242 | const char * | |
243 | get_oserror (void) | |
244 | { | |
245 | ||
246 | return strerror (errno); | |
247 | } | |
248 | ||
249 | ||
250 | /* sys_exit()-- Terminate the program with an exit code */ | |
251 | ||
252 | void | |
253 | sys_exit (int code) | |
254 | { | |
255 | ||
256 | exit (code); | |
257 | } | |
258 | ||
259 | ||
260 | ||
261 | /********************************************************************* | |
262 | File descriptor stream functions | |
263 | *********************************************************************/ | |
264 | ||
265 | /* fd_flush()-- Write bytes that need to be written */ | |
266 | ||
267 | static try | |
268 | fd_flush (unix_stream * s) | |
269 | { | |
270 | ||
271 | if (s->ndirty == 0) | |
272 | return SUCCESS;; | |
273 | ||
274 | if (s->physical_offset != s->dirty_offset && | |
275 | lseek (s->fd, s->dirty_offset, SEEK_SET) < 0) | |
276 | return FAILURE; | |
277 | ||
278 | if (writen (s->fd, s->buffer + (s->dirty_offset - s->buffer_offset), | |
279 | s->ndirty) < 0) | |
280 | return FAILURE; | |
281 | ||
282 | s->physical_offset = s->dirty_offset + s->ndirty; | |
bf1df0a0 BD |
283 | |
284 | /* don't increment file_length if the file is non-seekable */ | |
285 | if (s->file_length != -1 && s->physical_offset > s->file_length) | |
6de9cd9a DN |
286 | s->file_length = s->physical_offset; |
287 | s->ndirty = 0; | |
288 | ||
289 | return SUCCESS; | |
290 | } | |
291 | ||
292 | ||
293 | /* fd_alloc()-- Arrange a buffer such that the salloc() request can be | |
294 | * satisfied. This subroutine gets the buffer ready for whatever is | |
295 | * to come next. */ | |
296 | ||
297 | static void | |
81f4be3c | 298 | fd_alloc (unix_stream * s, gfc_offset where, int *len) |
6de9cd9a DN |
299 | { |
300 | char *new_buffer; | |
301 | int n, read_len; | |
302 | ||
303 | if (*len <= BUFFER_SIZE) | |
304 | { | |
305 | new_buffer = s->small_buffer; | |
306 | read_len = BUFFER_SIZE; | |
307 | } | |
308 | else | |
309 | { | |
310 | new_buffer = get_mem (*len); | |
311 | read_len = *len; | |
312 | } | |
313 | ||
314 | /* Salvage bytes currently within the buffer. This is important for | |
315 | * devices that cannot seek. */ | |
316 | ||
317 | if (s->buffer != NULL && s->buffer_offset <= where && | |
318 | where <= s->buffer_offset + s->active) | |
319 | { | |
320 | ||
321 | n = s->active - (where - s->buffer_offset); | |
322 | memmove (new_buffer, s->buffer + (where - s->buffer_offset), n); | |
323 | ||
324 | s->active = n; | |
325 | } | |
326 | else | |
327 | { /* new buffer starts off empty */ | |
328 | s->active = 0; | |
329 | } | |
330 | ||
331 | s->buffer_offset = where; | |
332 | ||
333 | /* free the old buffer if necessary */ | |
334 | ||
335 | if (s->buffer != NULL && s->buffer != s->small_buffer) | |
336 | free_mem (s->buffer); | |
337 | ||
338 | s->buffer = new_buffer; | |
339 | s->len = read_len; | |
340 | s->mmaped = 0; | |
341 | } | |
342 | ||
343 | ||
344 | /* fd_alloc_r_at()-- Allocate a stream buffer for reading. Either | |
345 | * we've already buffered the data or we need to load it. Returns | |
346 | * NULL on I/O error. */ | |
347 | ||
348 | static char * | |
81f4be3c | 349 | fd_alloc_r_at (unix_stream * s, int *len, gfc_offset where) |
6de9cd9a | 350 | { |
81f4be3c | 351 | gfc_offset m; |
6de9cd9a DN |
352 | int n; |
353 | ||
354 | if (where == -1) | |
355 | where = s->logical_offset; | |
356 | ||
357 | if (s->buffer != NULL && s->buffer_offset <= where && | |
358 | where + *len <= s->buffer_offset + s->active) | |
359 | { | |
360 | ||
361 | /* Return a position within the current buffer */ | |
362 | ||
363 | s->logical_offset = where + *len; | |
364 | return s->buffer + where - s->buffer_offset; | |
365 | } | |
366 | ||
367 | fd_alloc (s, where, len); | |
368 | ||
369 | m = where + s->active; | |
370 | ||
371 | if (s->physical_offset != m && lseek (s->fd, m, SEEK_SET) < 0) | |
372 | return NULL; | |
373 | ||
374 | n = read (s->fd, s->buffer + s->active, s->len - s->active); | |
375 | if (n < 0) | |
376 | return NULL; | |
377 | ||
378 | s->physical_offset = where + n; | |
379 | ||
380 | s->active += n; | |
381 | if (s->active < *len) | |
382 | *len = s->active; /* Bytes actually available */ | |
383 | ||
384 | s->logical_offset = where + *len; | |
385 | ||
386 | return s->buffer; | |
387 | } | |
388 | ||
389 | ||
390 | /* fd_alloc_w_at()-- Allocate a stream buffer for writing. Either | |
391 | * we've already buffered the data or we need to load it. */ | |
392 | ||
393 | static char * | |
81f4be3c | 394 | fd_alloc_w_at (unix_stream * s, int *len, gfc_offset where) |
6de9cd9a | 395 | { |
81f4be3c | 396 | gfc_offset n; |
6de9cd9a DN |
397 | |
398 | if (where == -1) | |
399 | where = s->logical_offset; | |
400 | ||
401 | if (s->buffer == NULL || s->buffer_offset > where || | |
402 | where + *len > s->buffer_offset + s->len) | |
403 | { | |
404 | ||
405 | if (fd_flush (s) == FAILURE) | |
406 | return NULL; | |
407 | fd_alloc (s, where, len); | |
408 | } | |
409 | ||
410 | /* Return a position within the current buffer */ | |
bf1df0a0 BD |
411 | if (s->ndirty == 0 |
412 | || where > s->dirty_offset + s->ndirty | |
413 | || s->dirty_offset > where + *len) | |
414 | { /* Discontiguous blocks, start with a clean buffer. */ | |
415 | /* Flush the buffer. */ | |
416 | if (s->ndirty != 0) | |
417 | fd_flush (s); | |
418 | s->dirty_offset = where; | |
419 | s->ndirty = *len; | |
6de9cd9a DN |
420 | } |
421 | else | |
bf1df0a0 BD |
422 | { |
423 | gfc_offset start; /* Merge with the existing data. */ | |
424 | if (where < s->dirty_offset) | |
425 | start = where; | |
426 | else | |
427 | start = s->dirty_offset; | |
428 | if (where + *len > s->dirty_offset + s->ndirty) | |
429 | s->ndirty = where + *len - start; | |
430 | else | |
431 | s->ndirty = s->dirty_offset + s->ndirty - start; | |
432 | s->dirty_offset = start; | |
6de9cd9a DN |
433 | } |
434 | ||
435 | s->logical_offset = where + *len; | |
436 | ||
437 | n = s->logical_offset - s->buffer_offset; | |
438 | if (n > s->active) | |
439 | s->active = n; | |
440 | ||
441 | return s->buffer + where - s->buffer_offset; | |
442 | } | |
443 | ||
444 | ||
445 | static try | |
446 | fd_sfree (unix_stream * s) | |
447 | { | |
448 | ||
449 | if (s->ndirty != 0 && | |
450 | (s->buffer != s->small_buffer || options.all_unbuffered || | |
451 | s->unbuffered)) | |
452 | return fd_flush (s); | |
453 | ||
454 | return SUCCESS; | |
455 | } | |
456 | ||
457 | ||
458 | static int | |
81f4be3c | 459 | fd_seek (unix_stream * s, gfc_offset offset) |
6de9cd9a DN |
460 | { |
461 | ||
462 | s->physical_offset = s->logical_offset = offset; | |
463 | ||
464 | return (lseek (s->fd, offset, SEEK_SET) < 0) ? FAILURE : SUCCESS; | |
465 | } | |
466 | ||
467 | ||
468 | /* truncate_file()-- Given a unit, truncate the file at the current | |
469 | * position. Sets the physical location to the new end of the file. | |
470 | * Returns nonzero on error. */ | |
471 | ||
472 | static try | |
473 | fd_truncate (unix_stream * s) | |
474 | { | |
475 | ||
bf1df0a0 | 476 | if (lseek (s->fd, s->logical_offset, SEEK_SET) == -1) |
6de9cd9a DN |
477 | return FAILURE; |
478 | ||
bf1df0a0 BD |
479 | /* non-seekable files, like terminals and fifo's fail the lseek. |
480 | the fd is a regular file at this point */ | |
6de9cd9a | 481 | |
bf1df0a0 BD |
482 | if (ftruncate (s->fd, s->logical_offset)) |
483 | { | |
6de9cd9a | 484 | return FAILURE; |
bf1df0a0 BD |
485 | } |
486 | ||
487 | s->physical_offset = s->file_length = s->logical_offset; | |
6de9cd9a DN |
488 | |
489 | return SUCCESS; | |
490 | } | |
491 | ||
492 | ||
493 | static try | |
494 | fd_close (unix_stream * s) | |
495 | { | |
496 | ||
497 | if (fd_flush (s) == FAILURE) | |
498 | return FAILURE; | |
499 | ||
500 | if (s->buffer != NULL && s->buffer != s->small_buffer) | |
501 | free_mem (s->buffer); | |
502 | ||
503 | if (close (s->fd) < 0) | |
504 | return FAILURE; | |
505 | ||
506 | free_mem (s); | |
507 | ||
508 | return SUCCESS; | |
509 | } | |
510 | ||
511 | ||
512 | static void | |
513 | fd_open (unix_stream * s) | |
514 | { | |
515 | ||
516 | if (isatty (s->fd)) | |
517 | s->unbuffered = 1; | |
518 | ||
519 | s->st.alloc_r_at = (void *) fd_alloc_r_at; | |
520 | s->st.alloc_w_at = (void *) fd_alloc_w_at; | |
521 | s->st.sfree = (void *) fd_sfree; | |
522 | s->st.close = (void *) fd_close; | |
523 | s->st.seek = (void *) fd_seek; | |
524 | s->st.truncate = (void *) fd_truncate; | |
525 | ||
526 | s->buffer = NULL; | |
527 | } | |
528 | ||
529 | ||
530 | /********************************************************************* | |
531 | mmap stream functions | |
532 | ||
533 | Because mmap() is not capable of extending a file, we have to keep | |
534 | track of how long the file is. We also have to be able to detect end | |
535 | of file conditions. If there are multiple writers to the file (which | |
536 | can only happen outside the current program), things will get | |
537 | confused. Then again, things will get confused anyway. | |
538 | ||
539 | *********************************************************************/ | |
540 | ||
541 | #if HAVE_MMAP | |
542 | ||
543 | static int page_size, page_mask; | |
544 | ||
545 | /* mmap_flush()-- Deletes a memory mapping if something is mapped. */ | |
546 | ||
547 | static try | |
548 | mmap_flush (unix_stream * s) | |
549 | { | |
550 | ||
551 | if (!s->mmaped) | |
552 | return fd_flush (s); | |
553 | ||
554 | if (s->buffer == NULL) | |
555 | return SUCCESS; | |
556 | ||
557 | if (munmap (s->buffer, s->active)) | |
558 | return FAILURE; | |
559 | ||
560 | s->buffer = NULL; | |
561 | s->active = 0; | |
562 | ||
563 | return SUCCESS; | |
564 | } | |
565 | ||
566 | ||
567 | /* mmap_alloc()-- mmap() a section of the file. The whole section is | |
568 | * guaranteed to be mappable. */ | |
569 | ||
570 | static try | |
81f4be3c | 571 | mmap_alloc (unix_stream * s, gfc_offset where, int *len) |
6de9cd9a | 572 | { |
81f4be3c | 573 | gfc_offset offset; |
6de9cd9a DN |
574 | int length; |
575 | char *p; | |
576 | ||
577 | if (mmap_flush (s) == FAILURE) | |
578 | return FAILURE; | |
579 | ||
580 | offset = where & page_mask; /* Round down to the next page */ | |
581 | ||
582 | length = ((where - offset) & page_mask) + 2 * page_size; | |
583 | ||
584 | p = mmap (NULL, length, s->prot, MAP_SHARED, s->fd, offset); | |
585 | if (p == (char *) MAP_FAILED) | |
586 | return FAILURE; | |
587 | ||
588 | s->mmaped = 1; | |
589 | s->buffer = p; | |
590 | s->buffer_offset = offset; | |
591 | s->active = length; | |
592 | ||
593 | return SUCCESS; | |
594 | } | |
595 | ||
596 | ||
597 | static char * | |
81f4be3c | 598 | mmap_alloc_r_at (unix_stream * s, int *len, gfc_offset where) |
6de9cd9a | 599 | { |
81f4be3c | 600 | gfc_offset m; |
6de9cd9a DN |
601 | |
602 | if (where == -1) | |
603 | where = s->logical_offset; | |
604 | ||
605 | m = where + *len; | |
606 | ||
607 | if ((s->buffer == NULL || s->buffer_offset > where || | |
608 | m > s->buffer_offset + s->active) && | |
609 | mmap_alloc (s, where, len) == FAILURE) | |
610 | return NULL; | |
611 | ||
612 | if (m > s->file_length) | |
613 | { | |
614 | *len = s->file_length - s->logical_offset; | |
615 | s->logical_offset = s->file_length; | |
616 | } | |
617 | else | |
618 | s->logical_offset = m; | |
619 | ||
620 | return s->buffer + (where - s->buffer_offset); | |
621 | } | |
622 | ||
623 | ||
624 | static char * | |
81f4be3c | 625 | mmap_alloc_w_at (unix_stream * s, int *len, gfc_offset where) |
6de9cd9a DN |
626 | { |
627 | if (where == -1) | |
628 | where = s->logical_offset; | |
629 | ||
630 | /* If we're extending the file, we have to use file descriptor | |
631 | * methods. */ | |
632 | ||
633 | if (where + *len > s->file_length) | |
634 | { | |
635 | if (s->mmaped) | |
636 | mmap_flush (s); | |
637 | return fd_alloc_w_at (s, len, where); | |
638 | } | |
639 | ||
640 | if ((s->buffer == NULL || s->buffer_offset > where || | |
641 | where + *len > s->buffer_offset + s->active) && | |
642 | mmap_alloc (s, where, len) == FAILURE) | |
643 | return NULL; | |
644 | ||
645 | s->logical_offset = where + *len; | |
646 | ||
647 | return s->buffer + where - s->buffer_offset; | |
648 | } | |
649 | ||
650 | ||
651 | static int | |
81f4be3c | 652 | mmap_seek (unix_stream * s, gfc_offset offset) |
6de9cd9a DN |
653 | { |
654 | ||
655 | s->logical_offset = offset; | |
656 | return SUCCESS; | |
657 | } | |
658 | ||
659 | ||
660 | static try | |
661 | mmap_close (unix_stream * s) | |
662 | { | |
663 | try t; | |
664 | ||
665 | t = mmap_flush (s); | |
666 | ||
667 | if (close (s->fd) < 0) | |
668 | t = FAILURE; | |
669 | free_mem (s); | |
670 | ||
671 | return t; | |
672 | } | |
673 | ||
674 | ||
675 | static try | |
676 | mmap_sfree (unix_stream * s) | |
677 | { | |
678 | ||
679 | return SUCCESS; | |
680 | } | |
681 | ||
682 | ||
683 | /* mmap_open()-- mmap_specific open. If the particular file cannot be | |
684 | * mmap()-ed, we fall back to the file descriptor functions. */ | |
685 | ||
686 | static try | |
687 | mmap_open (unix_stream * s) | |
688 | { | |
689 | char *p; | |
690 | int i; | |
691 | ||
692 | page_size = getpagesize (); | |
693 | page_mask = ~0; | |
694 | ||
695 | p = mmap (0, page_size, s->prot, MAP_SHARED, s->fd, 0); | |
696 | if (p == (char *) MAP_FAILED) | |
697 | { | |
698 | fd_open (s); | |
699 | return SUCCESS; | |
700 | } | |
701 | ||
702 | munmap (p, page_size); | |
703 | ||
704 | i = page_size >> 1; | |
705 | while (i != 0) | |
706 | { | |
707 | page_mask <<= 1; | |
708 | i >>= 1; | |
709 | } | |
710 | ||
711 | s->st.alloc_r_at = (void *) mmap_alloc_r_at; | |
712 | s->st.alloc_w_at = (void *) mmap_alloc_w_at; | |
713 | s->st.sfree = (void *) mmap_sfree; | |
714 | s->st.close = (void *) mmap_close; | |
715 | s->st.seek = (void *) mmap_seek; | |
716 | s->st.truncate = (void *) fd_truncate; | |
717 | ||
718 | if (lseek (s->fd, s->file_length, SEEK_SET) < 0) | |
719 | return FAILURE; | |
720 | ||
721 | return SUCCESS; | |
722 | } | |
723 | ||
724 | #endif | |
725 | ||
726 | ||
727 | /********************************************************************* | |
728 | memory stream functions - These are used for internal files | |
729 | ||
730 | The idea here is that a single stream structure is created and all | |
731 | requests must be satisfied from it. The location and size of the | |
732 | buffer is the character variable supplied to the READ or WRITE | |
733 | statement. | |
734 | ||
735 | *********************************************************************/ | |
736 | ||
737 | ||
738 | static char * | |
81f4be3c | 739 | mem_alloc_r_at (unix_stream * s, int *len, gfc_offset where) |
6de9cd9a | 740 | { |
81f4be3c | 741 | gfc_offset n; |
6de9cd9a DN |
742 | |
743 | if (where == -1) | |
744 | where = s->logical_offset; | |
745 | ||
746 | if (where < s->buffer_offset || where > s->buffer_offset + s->active) | |
747 | return NULL; | |
748 | ||
6de9cd9a DN |
749 | s->logical_offset = where + *len; |
750 | ||
bd72d66c | 751 | n = s->buffer_offset + s->active - where; |
6de9cd9a DN |
752 | if (*len > n) |
753 | *len = n; | |
754 | ||
755 | return s->buffer + (where - s->buffer_offset); | |
756 | } | |
757 | ||
758 | ||
759 | static char * | |
81f4be3c | 760 | mem_alloc_w_at (unix_stream * s, int *len, gfc_offset where) |
6de9cd9a | 761 | { |
81f4be3c | 762 | gfc_offset m; |
6de9cd9a DN |
763 | |
764 | if (where == -1) | |
765 | where = s->logical_offset; | |
766 | ||
767 | m = where + *len; | |
768 | ||
769 | if (where < s->buffer_offset || m > s->buffer_offset + s->active) | |
770 | return NULL; | |
771 | ||
772 | s->logical_offset = m; | |
773 | ||
774 | return s->buffer + (where - s->buffer_offset); | |
775 | } | |
776 | ||
777 | ||
778 | static int | |
81f4be3c | 779 | mem_seek (unix_stream * s, gfc_offset offset) |
6de9cd9a DN |
780 | { |
781 | ||
782 | if (offset > s->file_length) | |
783 | { | |
784 | errno = ESPIPE; | |
785 | return FAILURE; | |
786 | } | |
787 | ||
788 | s->logical_offset = offset; | |
789 | return SUCCESS; | |
790 | } | |
791 | ||
792 | ||
793 | static int | |
794 | mem_truncate (unix_stream * s) | |
795 | { | |
796 | ||
797 | return SUCCESS; | |
798 | } | |
799 | ||
800 | ||
801 | static try | |
802 | mem_close (unix_stream * s) | |
803 | { | |
804 | ||
805 | return SUCCESS; | |
806 | } | |
807 | ||
808 | ||
809 | static try | |
810 | mem_sfree (unix_stream * s) | |
811 | { | |
812 | ||
813 | return SUCCESS; | |
814 | } | |
815 | ||
816 | ||
817 | ||
818 | /********************************************************************* | |
819 | Public functions -- A reimplementation of this module needs to | |
820 | define functional equivalents of the following. | |
821 | *********************************************************************/ | |
822 | ||
823 | /* empty_internal_buffer()-- Zero the buffer of Internal file */ | |
824 | ||
825 | void | |
826 | empty_internal_buffer(stream *strm) | |
827 | { | |
828 | unix_stream * s = (unix_stream *) strm; | |
829 | memset(s->buffer, ' ', s->file_length); | |
830 | } | |
831 | ||
832 | /* open_internal()-- Returns a stream structure from an internal file */ | |
833 | ||
834 | stream * | |
835 | open_internal (char *base, int length) | |
836 | { | |
837 | unix_stream *s; | |
838 | ||
839 | s = get_mem (sizeof (unix_stream)); | |
840 | ||
841 | s->buffer = base; | |
842 | s->buffer_offset = 0; | |
843 | ||
844 | s->logical_offset = 0; | |
845 | s->active = s->file_length = length; | |
846 | ||
847 | s->st.alloc_r_at = (void *) mem_alloc_r_at; | |
848 | s->st.alloc_w_at = (void *) mem_alloc_w_at; | |
849 | s->st.sfree = (void *) mem_sfree; | |
850 | s->st.close = (void *) mem_close; | |
851 | s->st.seek = (void *) mem_seek; | |
852 | s->st.truncate = (void *) mem_truncate; | |
853 | ||
854 | return (stream *) s; | |
855 | } | |
856 | ||
857 | ||
858 | /* fd_to_stream()-- Given an open file descriptor, build a stream | |
859 | * around it. */ | |
860 | ||
861 | static stream * | |
862 | fd_to_stream (int fd, int prot) | |
863 | { | |
864 | struct stat statbuf; | |
865 | unix_stream *s; | |
866 | ||
867 | s = get_mem (sizeof (unix_stream)); | |
868 | ||
869 | s->fd = fd; | |
870 | s->buffer_offset = 0; | |
871 | s->physical_offset = 0; | |
872 | s->logical_offset = 0; | |
873 | s->prot = prot; | |
874 | ||
875 | /* Get the current length of the file. */ | |
876 | ||
877 | fstat (fd, &statbuf); | |
878 | s->file_length = S_ISREG (statbuf.st_mode) ? statbuf.st_size : -1; | |
879 | ||
880 | #if HAVE_MMAP | |
881 | mmap_open (s); | |
882 | #else | |
883 | fd_open (s); | |
884 | #endif | |
885 | ||
886 | return (stream *) s; | |
887 | } | |
888 | ||
889 | ||
890 | /* unpack_filename()-- Given a fortran string and a pointer to a | |
891 | * buffer that is PATH_MAX characters, convert the fortran string to a | |
892 | * C string in the buffer. Returns nonzero if this is not possible. */ | |
893 | ||
894 | static int | |
895 | unpack_filename (char *cstring, const char *fstring, int len) | |
896 | { | |
897 | ||
898 | len = fstrlen (fstring, len); | |
899 | if (len >= PATH_MAX) | |
900 | return 1; | |
901 | ||
902 | memmove (cstring, fstring, len); | |
903 | cstring[len] = '\0'; | |
904 | ||
905 | return 0; | |
906 | } | |
907 | ||
908 | ||
909 | /* tempfile()-- Generate a temporary filename for a scratch file and | |
910 | * open it. mkstemp() opens the file for reading and writing, but the | |
911 | * library mode prevents anything that is not allowed. The descriptor | |
912 | * is returns, which is less than zero on error. The template is | |
913 | * pointed to by ioparm.file, which is copied into the unit structure | |
914 | * and freed later. */ | |
915 | ||
916 | static int | |
917 | tempfile (void) | |
918 | { | |
919 | const char *tempdir; | |
920 | char *template; | |
921 | int fd; | |
922 | ||
923 | tempdir = getenv ("GFORTRAN_TMPDIR"); | |
924 | if (tempdir == NULL) | |
925 | tempdir = getenv ("TMP"); | |
926 | if (tempdir == NULL) | |
927 | tempdir = DEFAULT_TEMPDIR; | |
928 | ||
929 | template = get_mem (strlen (tempdir) + 20); | |
930 | ||
931 | st_sprintf (template, "%s/gfortantmpXXXXXX", tempdir); | |
932 | ||
933 | fd = mkstemp (template); | |
934 | ||
935 | if (fd < 0) | |
936 | free_mem (template); | |
937 | else | |
938 | { | |
939 | ioparm.file = template; | |
940 | ioparm.file_len = strlen (template); /* Don't include trailing nul */ | |
941 | } | |
942 | ||
943 | return fd; | |
944 | } | |
945 | ||
946 | ||
947 | /* regular_file()-- Open a regular file. Returns the descriptor, which is less than zero on error. */ | |
948 | ||
949 | static int | |
950 | regular_file (unit_action action, unit_status status) | |
951 | { | |
952 | char path[PATH_MAX + 1]; | |
953 | struct stat statbuf; | |
954 | int mode; | |
955 | ||
956 | if (unpack_filename (path, ioparm.file, ioparm.file_len)) | |
957 | { | |
958 | errno = ENOENT; /* Fake an OS error */ | |
959 | return -1; | |
960 | } | |
961 | ||
962 | mode = 0; | |
963 | ||
964 | switch (action) | |
965 | { | |
966 | case ACTION_READ: | |
967 | mode = O_RDONLY; | |
968 | break; | |
969 | ||
970 | case ACTION_WRITE: | |
971 | mode = O_WRONLY; | |
972 | break; | |
973 | ||
974 | case ACTION_READWRITE: | |
975 | mode = O_RDWR; | |
976 | break; | |
977 | ||
978 | default: | |
979 | internal_error ("regular_file(): Bad action"); | |
980 | } | |
981 | ||
982 | switch (status) | |
983 | { | |
984 | case STATUS_NEW: | |
985 | mode |= O_CREAT | O_EXCL; | |
986 | break; | |
987 | ||
988 | case STATUS_OLD: /* file must exist, so check for its existence */ | |
989 | if (stat (path, &statbuf) < 0) | |
990 | return -1; | |
991 | break; | |
992 | ||
993 | case STATUS_UNKNOWN: | |
994 | case STATUS_SCRATCH: | |
995 | mode |= O_CREAT; | |
996 | break; | |
997 | ||
998 | case STATUS_REPLACE: | |
3e14aaa2 | 999 | mode |= O_CREAT | O_TRUNC; |
6de9cd9a DN |
1000 | break; |
1001 | ||
1002 | default: | |
1003 | internal_error ("regular_file(): Bad status"); | |
1004 | } | |
1005 | ||
1006 | // mode |= O_LARGEFILE; | |
1007 | ||
1008 | return open (path, mode, | |
1009 | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH); | |
1010 | } | |
1011 | ||
1012 | ||
1013 | /* open_external()-- Open an external file, unix specific version. | |
1014 | * Returns NULL on operating system error. */ | |
1015 | ||
1016 | stream * | |
1017 | open_external (unit_action action, unit_status status) | |
1018 | { | |
1019 | int fd, prot; | |
1020 | ||
1021 | fd = | |
1022 | (status == STATUS_SCRATCH) ? tempfile () : regular_file (action, status); | |
1023 | ||
1024 | if (fd < 0) | |
1025 | return NULL; | |
1026 | fd = fix_fd (fd); | |
1027 | ||
1028 | switch (action) | |
1029 | { | |
1030 | case ACTION_READ: | |
1031 | prot = PROT_READ; | |
1032 | break; | |
1033 | ||
1034 | case ACTION_WRITE: | |
1035 | prot = PROT_WRITE; | |
1036 | break; | |
1037 | ||
1038 | case ACTION_READWRITE: | |
1039 | prot = PROT_READ | PROT_WRITE; | |
1040 | break; | |
1041 | ||
1042 | default: | |
1043 | internal_error ("open_external(): Bad action"); | |
1044 | } | |
1045 | ||
1046 | /* If this is a scratch file, we can unlink it now and the file will | |
1047 | * go away when it is closed. */ | |
1048 | ||
1049 | if (status == STATUS_SCRATCH) | |
1050 | unlink (ioparm.file); | |
1051 | ||
1052 | return fd_to_stream (fd, prot); | |
1053 | } | |
1054 | ||
1055 | ||
1056 | /* input_stream()-- Return a stream pointer to the default input stream. | |
1057 | * Called on initialization. */ | |
1058 | ||
1059 | stream * | |
1060 | input_stream (void) | |
1061 | { | |
1062 | ||
1063 | return fd_to_stream (STDIN_FILENO, PROT_READ); | |
1064 | } | |
1065 | ||
1066 | ||
1067 | /* output_stream()-- Return a stream pointer to the default input stream. | |
1068 | * Called on initialization. */ | |
1069 | ||
1070 | stream * | |
1071 | output_stream (void) | |
1072 | { | |
1073 | ||
1074 | return fd_to_stream (STDOUT_FILENO, PROT_WRITE); | |
1075 | } | |
1076 | ||
1077 | ||
1078 | /* init_error_stream()-- Return a pointer to the error stream. This | |
1079 | * subroutine is called when the stream is needed, rather than at | |
1080 | * initialization. We want to work even if memory has been seriously | |
1081 | * corrupted. */ | |
1082 | ||
1083 | stream * | |
1084 | init_error_stream (void) | |
1085 | { | |
1086 | static unix_stream error; | |
1087 | ||
1088 | memset (&error, '\0', sizeof (error)); | |
1089 | ||
1090 | error.fd = options.use_stderr ? STDERR_FILENO : STDOUT_FILENO; | |
1091 | ||
1092 | error.st.alloc_w_at = (void *) fd_alloc_w_at; | |
1093 | error.st.sfree = (void *) fd_sfree; | |
1094 | ||
1095 | error.unbuffered = 1; | |
1096 | error.buffer = error.small_buffer; | |
1097 | ||
1098 | return (stream *) & error; | |
1099 | } | |
1100 | ||
1101 | ||
1102 | /* compare_file_filename()-- Given an open stream and a fortran string | |
1103 | * that is a filename, figure out if the file is the same as the | |
1104 | * filename. */ | |
1105 | ||
1106 | int | |
1107 | compare_file_filename (stream * s, const char *name, int len) | |
1108 | { | |
1109 | char path[PATH_MAX + 1]; | |
1110 | struct stat st1, st2; | |
1111 | ||
1112 | if (unpack_filename (path, name, len)) | |
1113 | return 0; /* Can't be the same */ | |
1114 | ||
1115 | /* If the filename doesn't exist, then there is no match with the | |
1116 | * existing file. */ | |
1117 | ||
1118 | if (stat (path, &st1) < 0) | |
1119 | return 0; | |
1120 | ||
1121 | fstat (((unix_stream *) s)->fd, &st2); | |
1122 | ||
1123 | return (st1.st_dev == st2.st_dev) && (st1.st_ino == st2.st_ino); | |
1124 | } | |
1125 | ||
1126 | ||
1127 | /* find_file0()-- Recursive work function for find_file() */ | |
1128 | ||
909087e0 TS |
1129 | static gfc_unit * |
1130 | find_file0 (gfc_unit * u, struct stat *st1) | |
6de9cd9a DN |
1131 | { |
1132 | struct stat st2; | |
909087e0 | 1133 | gfc_unit *v; |
6de9cd9a DN |
1134 | |
1135 | if (u == NULL) | |
1136 | return NULL; | |
1137 | ||
1138 | if (fstat (((unix_stream *) u->s)->fd, &st2) >= 0 && | |
1139 | st1->st_dev == st2.st_dev && st1->st_ino == st2.st_ino) | |
1140 | return u; | |
1141 | ||
1142 | v = find_file0 (u->left, st1); | |
1143 | if (v != NULL) | |
1144 | return v; | |
1145 | ||
1146 | v = find_file0 (u->right, st1); | |
1147 | if (v != NULL) | |
1148 | return v; | |
1149 | ||
1150 | return NULL; | |
1151 | } | |
1152 | ||
1153 | ||
1154 | /* find_file()-- Take the current filename and see if there is a unit | |
1155 | * that has the file already open. Returns a pointer to the unit if so. */ | |
1156 | ||
909087e0 | 1157 | gfc_unit * |
6de9cd9a DN |
1158 | find_file (void) |
1159 | { | |
1160 | char path[PATH_MAX + 1]; | |
1161 | struct stat statbuf; | |
1162 | ||
1163 | if (unpack_filename (path, ioparm.file, ioparm.file_len)) | |
1164 | return NULL; | |
1165 | ||
1166 | if (stat (path, &statbuf) < 0) | |
1167 | return NULL; | |
1168 | ||
1169 | return find_file0 (g.unit_root, &statbuf); | |
1170 | } | |
1171 | ||
1172 | ||
1173 | /* stream_at_bof()-- Returns nonzero if the stream is at the beginning | |
1174 | * of the file. */ | |
1175 | ||
1176 | int | |
1177 | stream_at_bof (stream * s) | |
1178 | { | |
1179 | unix_stream *us; | |
1180 | ||
1181 | us = (unix_stream *) s; | |
1182 | ||
1183 | if (!us->mmaped) | |
1184 | return 0; /* File is not seekable */ | |
1185 | ||
1186 | return us->logical_offset == 0; | |
1187 | } | |
1188 | ||
1189 | ||
1190 | /* stream_at_eof()-- Returns nonzero if the stream is at the beginning | |
1191 | * of the file. */ | |
1192 | ||
1193 | int | |
1194 | stream_at_eof (stream * s) | |
1195 | { | |
1196 | unix_stream *us; | |
1197 | ||
1198 | us = (unix_stream *) s; | |
1199 | ||
1200 | if (!us->mmaped) | |
1201 | return 0; /* File is not seekable */ | |
1202 | ||
1203 | return us->logical_offset == us->dirty_offset; | |
1204 | } | |
1205 | ||
1206 | ||
1207 | /* delete_file()-- Given a unit structure, delete the file associated | |
1208 | * with the unit. Returns nonzero if something went wrong. */ | |
1209 | ||
1210 | int | |
909087e0 | 1211 | delete_file (gfc_unit * u) |
6de9cd9a DN |
1212 | { |
1213 | char path[PATH_MAX + 1]; | |
1214 | ||
1215 | if (unpack_filename (path, u->file, u->file_len)) | |
1216 | { /* Shouldn't be possible */ | |
1217 | errno = ENOENT; | |
1218 | return 1; | |
1219 | } | |
1220 | ||
1221 | return unlink (path); | |
1222 | } | |
1223 | ||
1224 | ||
1225 | /* file_exists()-- Returns nonzero if the current filename exists on | |
1226 | * the system */ | |
1227 | ||
1228 | int | |
1229 | file_exists (void) | |
1230 | { | |
1231 | char path[PATH_MAX + 1]; | |
1232 | struct stat statbuf; | |
1233 | ||
1234 | if (unpack_filename (path, ioparm.file, ioparm.file_len)) | |
1235 | return 0; | |
1236 | ||
1237 | if (stat (path, &statbuf) < 0) | |
1238 | return 0; | |
1239 | ||
1240 | return 1; | |
1241 | } | |
1242 | ||
1243 | ||
1244 | ||
1245 | static const char *yes = "YES", *no = "NO", *unknown = "UNKNOWN"; | |
1246 | ||
1247 | /* inquire_sequential()-- Given a fortran string, determine if the | |
1248 | * file is suitable for sequential access. Returns a C-style | |
1249 | * string. */ | |
1250 | ||
1251 | const char * | |
1252 | inquire_sequential (const char *string, int len) | |
1253 | { | |
1254 | char path[PATH_MAX + 1]; | |
1255 | struct stat statbuf; | |
1256 | ||
1257 | if (string == NULL || | |
1258 | unpack_filename (path, string, len) || stat (path, &statbuf) < 0) | |
1259 | return unknown; | |
1260 | ||
1261 | if (S_ISREG (statbuf.st_mode) || | |
1262 | S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)) | |
1263 | return yes; | |
1264 | ||
1265 | if (S_ISDIR (statbuf.st_mode) || S_ISBLK (statbuf.st_mode)) | |
1266 | return no; | |
1267 | ||
1268 | return unknown; | |
1269 | } | |
1270 | ||
1271 | ||
1272 | /* inquire_direct()-- Given a fortran string, determine if the file is | |
1273 | * suitable for direct access. Returns a C-style string. */ | |
1274 | ||
1275 | const char * | |
1276 | inquire_direct (const char *string, int len) | |
1277 | { | |
1278 | char path[PATH_MAX + 1]; | |
1279 | struct stat statbuf; | |
1280 | ||
1281 | if (string == NULL || | |
1282 | unpack_filename (path, string, len) || stat (path, &statbuf) < 0) | |
1283 | return unknown; | |
1284 | ||
1285 | if (S_ISREG (statbuf.st_mode) || S_ISBLK (statbuf.st_mode)) | |
1286 | return yes; | |
1287 | ||
1288 | if (S_ISDIR (statbuf.st_mode) || | |
1289 | S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)) | |
1290 | return no; | |
1291 | ||
1292 | return unknown; | |
1293 | } | |
1294 | ||
1295 | ||
1296 | /* inquire_formatted()-- Given a fortran string, determine if the file | |
1297 | * is suitable for formatted form. Returns a C-style string. */ | |
1298 | ||
1299 | const char * | |
1300 | inquire_formatted (const char *string, int len) | |
1301 | { | |
1302 | char path[PATH_MAX + 1]; | |
1303 | struct stat statbuf; | |
1304 | ||
1305 | if (string == NULL || | |
1306 | unpack_filename (path, string, len) || stat (path, &statbuf) < 0) | |
1307 | return unknown; | |
1308 | ||
1309 | if (S_ISREG (statbuf.st_mode) || | |
1310 | S_ISBLK (statbuf.st_mode) || | |
1311 | S_ISCHR (statbuf.st_mode) || S_ISFIFO (statbuf.st_mode)) | |
1312 | return yes; | |
1313 | ||
1314 | if (S_ISDIR (statbuf.st_mode)) | |
1315 | return no; | |
1316 | ||
1317 | return unknown; | |
1318 | } | |
1319 | ||
1320 | ||
1321 | /* inquire_unformatted()-- Given a fortran string, determine if the file | |
1322 | * is suitable for unformatted form. Returns a C-style string. */ | |
1323 | ||
1324 | const char * | |
1325 | inquire_unformatted (const char *string, int len) | |
1326 | { | |
1327 | ||
1328 | return inquire_formatted (string, len); | |
1329 | } | |
1330 | ||
1331 | ||
1332 | /* inquire_access()-- Given a fortran string, determine if the file is | |
1333 | * suitable for access. */ | |
1334 | ||
1335 | static const char * | |
1336 | inquire_access (const char *string, int len, int mode) | |
1337 | { | |
1338 | char path[PATH_MAX + 1]; | |
1339 | ||
1340 | if (string == NULL || unpack_filename (path, string, len) || | |
1341 | access (path, mode) < 0) | |
1342 | return no; | |
1343 | ||
1344 | return yes; | |
1345 | } | |
1346 | ||
1347 | ||
1348 | /* inquire_read()-- Given a fortran string, determine if the file is | |
1349 | * suitable for READ access. */ | |
1350 | ||
1351 | const char * | |
1352 | inquire_read (const char *string, int len) | |
1353 | { | |
1354 | ||
1355 | return inquire_access (string, len, R_OK); | |
1356 | } | |
1357 | ||
1358 | ||
1359 | /* inquire_write()-- Given a fortran string, determine if the file is | |
1360 | * suitable for READ access. */ | |
1361 | ||
1362 | const char * | |
1363 | inquire_write (const char *string, int len) | |
1364 | { | |
1365 | ||
1366 | return inquire_access (string, len, W_OK); | |
1367 | } | |
1368 | ||
1369 | ||
1370 | /* inquire_readwrite()-- Given a fortran string, determine if the file is | |
1371 | * suitable for read and write access. */ | |
1372 | ||
1373 | const char * | |
1374 | inquire_readwrite (const char *string, int len) | |
1375 | { | |
1376 | ||
1377 | return inquire_access (string, len, R_OK | W_OK); | |
1378 | } | |
1379 | ||
1380 | ||
1381 | /* file_length()-- Return the file length in bytes, -1 if unknown */ | |
1382 | ||
81f4be3c | 1383 | gfc_offset |
6de9cd9a DN |
1384 | file_length (stream * s) |
1385 | { | |
1386 | ||
1387 | return ((unix_stream *) s)->file_length; | |
1388 | } | |
1389 | ||
1390 | ||
1391 | /* file_position()-- Return the current position of the file */ | |
1392 | ||
81f4be3c | 1393 | gfc_offset |
6de9cd9a DN |
1394 | file_position (stream * s) |
1395 | { | |
1396 | ||
1397 | return ((unix_stream *) s)->logical_offset; | |
1398 | } | |
1399 | ||
1400 | ||
1401 | /* is_seekable()-- Return nonzero if the stream is seekable, zero if | |
1402 | * it is not */ | |
1403 | ||
1404 | int | |
1405 | is_seekable (stream * s) | |
1406 | { | |
bf1df0a0 BD |
1407 | /* by convention, if file_length == -1, the file is not seekable |
1408 | note that a mmapped file is always seekable, an fd_ file may | |
1409 | or may not be. */ | |
1410 | return ((unix_stream *) s)->file_length!=-1; | |
6de9cd9a DN |
1411 | } |
1412 | ||
000aa32a JB |
1413 | try |
1414 | flush (stream *s) | |
1415 | { | |
1416 | return fd_flush( (unix_stream *) s); | |
1417 | } | |
1418 | ||
6de9cd9a DN |
1419 | |
1420 | /* How files are stored: This is an operating-system specific issue, | |
1421 | and therefore belongs here. There are three cases to consider. | |
1422 | ||
1423 | Direct Access: | |
1424 | Records are written as block of bytes corresponding to the record | |
1425 | length of the file. This goes for both formatted and unformatted | |
1426 | records. Positioning is done explicitly for each data transfer, | |
1427 | so positioning is not much of an issue. | |
1428 | ||
1429 | Sequential Formatted: | |
1430 | Records are separated by newline characters. The newline character | |
1431 | is prohibited from appearing in a string. If it does, this will be | |
1432 | messed up on the next read. End of file is also the end of a record. | |
1433 | ||
1434 | Sequential Unformatted: | |
1435 | In this case, we are merely copying bytes to and from main storage, | |
1436 | yet we need to keep track of varying record lengths. We adopt | |
1437 | the solution used by f2c. Each record contains a pair of length | |
1438 | markers: | |
1439 | ||
1440 | Length of record n in bytes | |
1441 | Data of record n | |
1442 | Length of record n in bytes | |
1443 | ||
1444 | Length of record n+1 in bytes | |
1445 | Data of record n+1 | |
1446 | Length of record n+1 in bytes | |
1447 | ||
1448 | The length is stored at the end of a record to allow backspacing to the | |
1449 | previous record. Between data transfer statements, the file pointer | |
1450 | is left pointing to the first length of the current record. | |
1451 | ||
1452 | ENDFILE records are never explicitly stored. | |
1453 | ||
1454 | */ |